For a potential employer or outsider, I would use a flyer. I would not use a letter, because a letter can be some what too formal for outsiders and a flyer is much easier to read and understand.
Flyer 1:
This is a flyer to announce that a job is now hiring. There isn't too much contrast is this flyer, but I like how the "Now Hiring" is in all red. So if this flyer was to be posted around, outsiders or potential employers will easily pay attention to it. The alignment is good. They asked a question at the beginning to relate to whoever is reading the flyer, then provided information underneath that question. They also lined up their contact information and lastly, pictures at the bottom of the flyer.
jobs-for-life-flyer.jpg

Flyer 2:
This is flyer for an event that is hosting a party. The contrast is good, because it sets the mood for a club scene at night by using dark colors in the background. I also like how they made the font white and bold, so that it would be very easy to read the information that is placed on the flyer. I don't like that there are different fonts. For a flyer, I think you should either use one or two fonts to categorized the information. The alignment is bad as well, everything is spaced out.
First_Class___Event_Flyer_by_xeon_art.jpg

Flyer 3:
This is a flyer for a job fair and out of all three flyers, this is my favorite one. I love the contrast, because it has style and the money green is a good color that you are able to read. The alignment is great as well. On one side of the flyer is information and on the other side have companies and contact information listed. Even though this flyer contains a lot of information, it does not look like it contains a lot of information because of the alignment. The green also reminds me of money and I think that is why they used it, because the flyer is for a job fair. This shows outsiders and potential employers that they are serious and took a lot of time to put into this flyer.
NOVA-AL-Campus-Job-Link-2014-Job-Fair_Flyer_For-Email-Ad-1.jpg

My flyer: